The invention relates to a ventilator or fan having a blocking device between its intake and pressure sides.
DE 30 48 571 A1 discloses a cross-flow fan having a nondeformable blocking device between its intake side and its pressure side. In the cross-flow fan the device may also serve as a turbulence former. A seal gap is formed between the rotor or the fan blades arranged on the rotor and the blocking device. With the known blocking device, this seal gap is necessary, since the rotor always has a residual imbalance, does not run one hundred percent true and/or is subject to dynamic deformation in operation, for example in the event of impact loads. However, the aerodynamic properties of the cross-flow fan are dependent, inter alia, on the size of the seal gap.
DE 195 27 605 A1 discloses, inter alia, a blocking device between a stator and a rotor of a turbo machine. The blocking device may be designed as a brush with bristle ends that keep the gap very small. However, this variant has a drawback in that a significantly audible rotational noise is generated when the rotor rotates. This noise may be perceived as a whistling or humming which may be disturbing to the user of the fans.